But doubts persist among evangelical voters who believe the Mormon faith clashes with their own beliefs. Many Christians have labelled Mormonism a 'cult'.

MIchael Otterson, managing director of the church's public affairs, told Sky News: "Obviously I would say that that is completely wrong."

Speaking at the Salt Lake City headquarters of the Church of Jesus Christ of Latter-day Saints, the official name of the Mormon church, he added: "In reality we have very good relations with evangelical churches, there is no religious war going on here.

"I think there is a genuine interest in trying to find out more about what we really believe."

The church has launched a television advertising campaign across the United States featuring people from all walks of life. Each ad ends with the line 'And I am a Mormon'.

The campaign is aimed at showing how Mormons are "just like everyone else" and is part of a wider effort to de-bunk some of the myths that persist about one of the fastest growing religions in the world.

But darker elements of the faith's history mean a stigma remains.

Stephen Mansfield, author of The Mormonizing of America, told Sky News: "It is regarded as a cult by almost 50 per cent of the country, religiously speaking.

"It has very unusual doctrines, it has been in a criminal status for a good proportion of its history, it has had racist and polygamist periods in its history so it's just not "normal"."

Mr Otterson said: "We abandoned polygamy in 1890."

Opinion polls disagree over whether Americans are ready to elect a Mormon to the White House but there is certainly less hostility than when Romney prepared a previous run 2007.

The former governor of Massachusetts is a bishop in the Mormon church who spent time as a missionary in France as a young man.

The church rarely allows television cameras into its churches but Sky News was invited to film a service in the Salt Lake City suburbs.

Michael and Kristy Coleman told us the increased attention on the church, the so-called 'Mormon Moment', had meant more questioning of believers.

Ms Coleman said: "it does open the doors for a lot of scrutiny but I don't like secrets, I think it is great.

"Knowledge squashes ignorance and I think the more people know first hand what Mormonism is about the better."

The Mormon church was founded by Joseph Smith in New York in 1830 and has now grown to an estimated 17 million followers around the world.